Automatic reclosing circuit breaker system



Sept. 20, 1938. L. w' DYER El AL 2,130,840

AUTOMATIC RECLOSING CIRCUIT BREAKER SYSTEM Filed Dec. 51. 1956 220 M AC.

WITNESSES: INVENTOR 5, L10 d N 0 er and WM y Patented Sept. 20, 1938UNITED STATES PATENT- OFFICE AUTOMATIC RECLOSING CIRCUIT BREAKER SYSTApplication December 31, 1936, Serial No. 118,564

4 Claims.

Our invention relates, generally, to circuit breaker systems and moreparticularly to automatic reclosing circuit breaker systems.

The object of our invention, generally stated, is to provide anautomatic reclosing circuit breaker system which comprises a simplesystem of inexpensive relays which may be economically manufactured andinstalled and which shall be simple, effective and reliable inoperation.

Another object of our invention is to provide an automatic reclosingcircuit breaker system which may be easily installed to operate circuitbreakers already in use in the field without requiring any specialapparatus to adapt such circuit breakers for use with the system.

Another object of our invention is to provide an automatic reclosingcircuit breaker system which may be economically installed to operatecircuit breakers already in use in the field by simple electrical andmechanical connections to such circuit breakers.

A further object of our invention is to provide an automatic reclosingcircuit breaker system which may be constructed of simple andinexpensive relays and switching devices which are well known in the artand are reliable in operation.

A further object of our invention is to provide an automatic reclosingcircuit breaker system which shall function to automatically reclose acircuit breaker at a predetermined interval after the opening of thebreaker.

Another object of our invention is to provide an automatic reclosingcircuit breaker system which shall function to reclose a circuit breakeron e2z1- piration of predetermined time intervals after each opening ofthe breaker.

Another object of our invention is to provide automatic reclosingcircuit breaker system which. shall function to reclose a circuitbreaker on ex piration of predetermined time intervals after eachopening of the breaker and to render the reclosing system inoperative toreclose the breaker at a predetermined time after the first opening ofthe breaker in the event that the breaker con. tinues to reopen uponbeing reclosed.

Another object of our invention is to provide automatic reclosingcircuit breaker system which shall function to reclose a circuit breakerat the expiration of a predetermined time after each opening of thebreaker and to render the reclosing system inoperative to reclose thebreaker at a time which shall 'depend upon the relative lengths of timethat the breaker remains in the closed and open position in any seriesof openings of the breaker in which the lengths of time between openingsof he breaker are relatively close to the length of time between openingand reclosing of the breaker.

Our invention is carried out, in its preferred form, by providing acontrol relay for the closing solenoid or other closing means of thecircuit breaker and this control relay is energized through contactswhich are closed at a predetermined time after the opening of thecircuit breaker and opened when the circuit breaker is closed. Thecircuit of the control relay is controlled by a normally-closed timedelayed relay, whose time delay is governed by the length of time thebreaker remains open, for locking out the circuit breaker reclosingsystem to prevent such a number of circm't breaker operations in a giventime period as might damage the breaker.

The apparatus comprising the automatic reclosing circuit breaker systemof our invention is illustrated diagrammatically in the single figure ofthe drawing.

Referring to the drawing, circuit breaker it connects the load circuitl2 to the supply circuit H. The usual tripping device l3, which iscontrolled by an overload coil M on the load side of the breaker It, isprovided to trip the breaker when an overload occurs on the line. Thebreaker is provided with a closing coil l5 which is cner gized throughthe contacts l6 and H of control relay it.

A contacting device it is controlled by the op crating mechanism of thebreaker l0 so that it is biased to the open position when the breaker isclosed, and is biased to the closed position when the breaker i0 is openthrougha loose mechanical connection illustrated diagrammatically byelemeat 20,

A time delay device ii is provided for delaying the closing of contactdevice It. This time delay device may be any means for delaying theclosing of contact device after the means for closing the contact devicehas operated. This device is shown as a dashpot which will retard theclosing of the contact device, but may be such a delayed action switchas is shown by the patents to Rhodes 1,773,697, August 19, 1930, or1,353,850, September 2?, 1920. Any other delayed action switch may beused for performing function of delaying the closing of contact deviceIS.

The delayed action switch device l9-2l is preferably adjustable so thatit may be set to obtain any desired delay between the opening of thecircuit breaker l0 and the closing of the contact dev ce l9. Contacts 22are connected to the ophit (ill) crating mechanism of the breaker I!) soas to be open when the breaker I0 is closed and closed when the breakeris opened.

A thermal current relay, generally designated by reference character 23,is controlled by contacts 22. This thermal relay comprises a heatingelement 24, a bimetallic element 25 and contacts The contacts arenormally closed and are opened upon predetermined heating oi element 24.A latching device 21 is provided to lock the contacts 26 in the openposition by engaging the bimetallic element 25 when it has moved the contacts 26 to open position. A variable resistance 34 is provided inseries with heating element 24 to vary the value of current flowing inheating element 34 and to thereby vary the time required to heat thebimetallic element 25 sufficiently to cause it to effect the opening ofcontacts 26.

The control power may be from the usual 220- volt, alternating currentor direct current source shown in the drawing as conductors X and Y. Thesystem as shown is operated on alternating current and has a rectifier28 connected between the circuit breaker closing coil l5 and its controlcontacts l6 and ll to obtain direct current for operating the closingcoil. This rectifier may be eliminated and the coil l5 connecteddirectly to contacts I6 and ii if direct current is used for the controlsystem.

The circuit for the closing coil of breaker extends from supplyconductor Y, through conductor 29, contacts ll, rectifier 28, closingcoil i5, contacts it and conductor 30 to supply conductor X. The circuitfor the control relay it which controls the energization of the closingcoil it extends from supply conductor Y, through conductor 3i, contactsiii, relay coil l8, contacts 26, bimetallic element 25, and conductors32 and 3d to supply conductor X.

The circuit for the thermal current relay 23 extends from supplyconductor Y, through conductor 33, contacts 22, adjustable resistance3d, heating element 24, contacts 26, bimetallic element iii andconductors 32 and Elli to supply conductor X.

When an overload occurs upon the line it, tripping device it isenergized to allow the circuit breaker to open to break the connectionbetween the supply line i t and the load circuit ill.

The opening of the circuit breaker biases contacts iii toward the closedposition and the closing of these contacts is delayed by the time delaydevice 2i. After the time delay determined by the device 2!! haselapsed, contacts iii close to complete the circuit through controlrelay The energization of relay it through contacts iii causes relay itto close its contacts in and [ill to energize closing coil in to reclosethe breaker. Thus the circuit breaker it is reclosed at a predeterminedtime after being tripped by the trip device 63, this time beingdetermined by the time delay of device it.

The reclosing of the circuit breaker iii causes contacts iii to openimmediately, deenergizing ccil ic The deenergizing of coil it causescontacts it and ill to open and to thereby deenergize the closing coilin of the circuit breaker.

The system has now been placed in normal operating position and if thefault which causes the original tripping of the circuit breaker stillexists. the breaker will immediately trip out through the agency ofoverload coil l4 and trip device l3 and the cycle of operation justdescribed will be repeated. Each time the breaker opens, contacts 22 areclosed immediately and remain closed for a time equal to the time delaygoverned by the time delay device 2| since they are closed so long asthe circuit breaker is open. While contacts 22 are closed, a circuit iscompleted through elements 33, 22, 34, 24, 26, 25, 32 and 3t. When thecircuit breaker i0 is reclosed, contacts 22 are immediately opened,breaking the circuit to the heating element 2t. Thus it is seen that theheating element 24 of the thermal current relay 23 is energized for theperiod that the circuit breaker is open.

If the circuit breaker l0 retrips immediately upon being reclosed,contacts 22 are again closed to energize heating coil 24 to causefurther heating of the thermal current relay.

In order to limit the number of reclosures of circuit breaker l0, and tothus protect it from damage due to too great a number of immediateopenings under the heavy load which is causing it to trip, the timedelay of thermal current relay 23 is adjusted by means of adjustableresistance M to open contacts 26 after a predetermined heating ofheating element 24 which is determined by the number of openings of thecircuit breaker Hi. If it is desired to limit the number of openings ofthe circuit breaker to three, resistance 34 will be adjusted so that thecurrent flowing through the heating element 24 for a period equal toslightly more than the time delay for reclosure of the circuit breakerwill cause the bimetallic element 25 to open contacts W'hen bimetallicelement 25 moves to a position to open contacts 26, it is locked bylatch means 21? in a position to hold contacts 26 open. Thus theenergizing circuit for coil 8 of the control relay is held open andautomatic reclosure of the circuit breaker i0 is prevented until latch27! is tripped.

The thermal current relay 23 may be adjusted by means of adjustableresistance 34 to cause any desired number of reclosures of the circuitbreaker before rendering the system for reclosing the circuit breakerinoperative. This may be done by adjusting the resistance 34 so that thecurrent through heating element 24 flowing for a period slightly greaterthan the sum of the desired number of open periods of the circuitbreaker it will operate to open and lock open contacts 28. This is thecondition that obtains ii? the circuit breaker immediately trips openafter each reclosure.

If the circuit breaker stays closed after any reclosure, the opening ofcontacts 212? will deenergize heating element 2d and allow bimetallicelement to cool to its normal temperature.

. it is understood that the thermal current relay and the time delaydevice 26 for delaying the closing or" contacts it] may be any devicefor performing the functions disclosed which are well known in the art.

Thus it is seen that we have provided a simple, inexpensive and reliablesystem for automatically reciosing a circuit breaker, which system willdelay the reclosing of the circuit breaker a desired predetermined timeafter the breaker is tripped open and which will limit the reclosings ofthe circuit breaker to any desired predeter mined number.

We claim as our invention:

1. in an automatic reclosinp; circuit breaker system, a circuit breakerbiased to open circuit position, latch means for holding the breaker inclosed position, means responsive to predetermined abnormal conditionson the circuit to which the breaker is connected for tripping said latchmeans, a first circuit closer, means whereby said first circuit closeris closed while said circuit breaker, is open and open while saidcircuit breaker is closed, a second circuit closer, means for closingsaid second circuit closer a predetermined time aiter said circuitbreaker is opened and 'ior opening said second circuit closer when saidcircuit breaker is closed, electromagnetic means for closingsaid circuitbreaker, a thermal current relay having a heating element, a circuitcomprising the contacts of said thermal current relay, the heatingelement of said thermal current relay and said first circuit closer forenergizing said heating element, a circuit comprising said thermalcurrent relay contacts, said circuit breaker closing means and saidsecond circuit closer for energizing said circuit breaker closing means,and means for retaining said thermal current relay contacts in opencircuit position.

2. In an automatic reclosing circuit breaker system, a circuit breakerbiased to open circuit position, mechanical latch means for holding saidcircuit breaker in closed circuit position, means responsive topredetermined abnormal conditions on the circuit to which *the circuitbreaker is connected i'or tripping said latch means, a first circuitcloser, means whereby movement of said circuit breaker to open circuitposition will close said first circuit closer and movement of saidcircuit breaker to closed circuit position will open said first circuitcloser, a second circuit closer.

, means whereby movement said circuit breaker circuit for energizingsaid heating element comprising the contacts of said thermal currentrelay, the heating element for said thermal current relay and said firstcircuit closer, and a circuit for energizing said circuit breakerclosing means comprising the thermal current relay contacts, saidcircuit breaker closing means and said second circuitcloser.

3. In a control system for a circuit breaker having an electricallyactuated closing means, first and second back contact elements on thecircuit breaker, said first back contact elements being time delayed inclosing upon opening of said circuit breaker, a thermal current relayhaving normally closed contact elements, a control circuit for thebreaker closing means comprising said first back contact elements andthe contact elements of said thermal current relay, and a circuitcomprising said second back contact elements and the heating element ofsaid thermal current relay, said control circuit for the breaker closingmeans being operable to deenergize the closing means when said circuitis broken by the movement of said first back contact elements to opencircuit position upon closing of said circuit breaker.

4. In a control system for a circuit breaker having an electricallyactuated closing means, first and second back contact elements actuatedby the circuit breaker, means providing delayed closing of said firstback contact elements upon opening of said circuit breaker, a thermalcurrent relay having normally closed contact elements, a first circuitconsisting of said first back contact elements, the circuit breakerclosing means, the thermal current relay contact elements connected inseries circuit relationship with a source of electric energy, and asecond circuit consisting of said second back contact elements which areopened when the circuit breaker is closed, the heating element of saidthermal current relay and the contact elements of said thermal currentrelay connected in series circuit relationship with a source of electricenergy.

LLOYD W. DYER. GAYNE D. GAMEL.

